1. Field of the Invention
The present invention relates to a control unit and in particular to a control unit for controlling the rapidity or the like of a lens to be controlled according to an operation of a control member.
2. Description of Related Art
A drive unit for rotating a zoom ring by means of a motor is attached at the side of a body tube of an ENG lens. The zoom control of the ENG lens is carried out according to user""s operation of a zoom seesaw switch provided on the drive unit. The zoom seesaw switch is swiveled by the operation in both directions from a standard position. The zoom seesaw switch returns to the standard position when the zoom seesaw switch is released from the operation (i.e., when the zoom seesaw switch is in a non-operation state). A potentiometer for determining the operational angle of the zoom seesaw switch is provided on the zoom seesaw switch. The potentiometer outputs a control signal corresponding to the operational angle of the zoom seesaw switch to a CPU for controlling the motor. In accordance with a value of the control signal given from the potentiometer, the CPU controls the rotating direction and the rapidity of the motor to rotate the zoom ring so as to control the moving direction and rapidity of a zoom lens. For example, upon pushing the zoom seesaw switch in one direction with respect to the standard position, the zoom lens moves in the telescopic view direction at the rapidity corresponding to the operational angle, whereas the zoom lens moves in the wide view direction opposed to the telescopic view direction at the rapidity corresponding to the operational angle upon pushing the zoom seesaw switch in the other direction opposed to the above, and further the zoom lens stops when the zoom seesaw switch is released from the operation.
The standard position of the zoom seesaw switch is a position where a control signal of zero is outputted from the potentiometer, i.e. a position to stop the zoom lens. The standard position is premised to be a return position to which the zoom seesaw switch returns when the zoom seesaw switch is released from the operation. However, there is the possibility of undesirable situations that the zoom lens does not stop even when the zoom seesaw switch is released from the operation, since the zoom seesaw switch does not always return to the standard position accurately depending on its return precision and the control signal does not always become zero even when the zoom seesaw switch is released from the operation. Hence, an insensitive zone is conventionally provided in the zoom seesaw switch so that the control signal never fails to become zero when the zoom seesaw switch is released from the operation. Japanese Patent Application Laid-Open No. 8-334673 discloses that the insensitive zone is so constructed that no change in operational angle can be sensed within a predetermined range of the operational angles and the control signal outputted from the potentiometer is so set as to become zero while the operational angle of the zoom seesaw switch comes within the predetermined range of the operational angles, i.e., within the insensitive zone.
Ideally, portions of the insensitive zone are equally allotted to the positive direction (e.g. the telescopic view direction) and the negative direction (e.g. the wide view direction) with respect to the standard position in the provision of the insensitive zone at the zoom seesaw switch. Actually, such an equal allotment is, however, difficult for all products in view of assembling. Besides, even if portions of the insensitive zone are equally allotted to the positive direction and the negative direction with respect to the standard position, the return position of the zoom seesaw switch does not always coincide with the standard position on account of errors in return precision as described above. Accordingly, when the zoom seesaw switch starts the operation in the positive direction or in the negative direction from the standard position, the operated quantity till the start of the zoom lens movement may be different between the positive direction and the negative direction. It is thus difficult for the user to operate the conventional zoom seesaw switch.
The present invention is achieved in consideration of such circumstances and it is one object of the present invention to provide a control unit capable of properly accomplishing the correspondence between the operational position of the operational member and the corresponding control contents in spite of variance in assembling precision and achieving an improvement in the operability of the operational member, a simplified assembly and the saving of manufacturing cost by permitting the setting and adjustment of the standard position of the operational member and an insensitive zone of the zoom seesaw switch to be electrically accomplished.
To attain the above object, the present invention is directed to a control unit which controls a control target, the control unit comprising: an operational member which is set at an operational position by an operation; a standard position setting instruction receiving device which receives a setting instruction to set a standard position with respect to the operational member; a standard position determining device which determines, at a time when the standard position setting instruction receiving device receives the setting instruction, the operational position of the operational member at the time as the standard position; and a control device which controls the control target under control contents in accordance with the operational position of the operational member, wherein the control contents over the control target when the operational member is at the standard position coincide with predetermined standard control contents over the control target.
Preferably, the control unit further comprises: a position determining device which determines the operational position of the operational member and outputs a control signal corresponding to the determined operational position, wherein the standard position determining device determines, at the time when the standard position setting instruction receiving device receives the setting instruction, a value of the control signal outputted from the position determining device at the time as a value representing the standard position, wherein the control device adjusts the value of the control signal outputted from the position determining device so that the value representing the standard position coincides with a predetermined standard value, and the control device controls the control target under the control contents in accordance with the adjusted value of the control signal.
Preferably, the control unit further comprises: a standard position setting instruction outputting device which outputs the setting instruction to set the standard position with respect to the operational member, wherein the standard position setting instruction receiving device receives the setting instruction outputted from the standard position setting instruction outputting device.
Preferably, the operational member returns to a return position when the operational member is released from the operation; and the standard position is set to the return position.
Preferably, the control unit controls the control target to move the control target at a rapidity according to the operational position of the operational member; and the control contents over the control target when the operational member is at the standard position is control to bring the control target to a stop.
The control target may be a moving lens in a lens apparatus.
The present invention is also directed to a control unit which controls a control target, the control unit comprising: an operational member which is set at an operational position by an operation; an insensitive zone size determining device which determines, when an insensitive zone including a predetermined standard position with respect to the operational member is set, a size of the insensitive zone; and a control device which controls the control target under control contents in accordance with the operational position of the operational member, wherein the control contents over the control target coincide, whenever a difference between the operational position of the operational member and the predetermined standard position is not more than the size of the insensitive zone determined by the insensitive zone size determining device, with the control contents over the control target when the operational member is at the standard position.
The present invention is also directed to a control unit which controls a control target, the control unit comprising: an operational member which is set at an operational position by an operation; a standard position setting instruction receiving device which receives a setting instruction to set a standard position with respect to the operational member; a standard position determining device which determines, at a time when the standard position setting instruction receiving device receives the setting instruction, the operational position of the operational member at the time as the standard position; an insensitive zone size determining device which determines, when an insensitive zone including the standard position determined by the standard position determining device is set, a size of the insensitive zone; and a control device which controls the control target under control contents in accordance with the operational position of the operational member, wherein the control contents over the control target coincide, whenever a difference between the operational position of the operational member and the predetermined standard position is not more than the size of the insensitive zone determined by the insensitive zone size determining device, with predetermined standard control contents over the control target.
Preferably, the control unit further comprises: a position determining device which determines the operational position of the operational member and outputs a control signal corresponding to the determined operational position, wherein the control contents over the control target coincide, whenever a difference between a value of the control signal outputted from the position determining device and a value representing the standard position is not more than the size of the insensitive zone determined by the insensitive zone size determining device, with the control contents corresponding to the value representing the standard position.
Preferably, the control unit further comprises: an insensitive zone size setting device which sets the size of the insensitive zone, wherein the insensitive zone size determining device determines the size of the insensitive zone set by the insensitive zone size setting device as the size of the insensitive zone.
According to the present invention, making the setting and adjustment of the standard position of the operational member and the insensitive zone of the operational member performable by the electric processing enables the correspondence between the operational position of the operational member and the corresponding control contents to be accurately and easily carried out. Thereby, an improvement in the operability of the operational member in all products can be achieved without variance in characteristics with individual products. During the assembly of products, no high precision in the adjustment of the standard position of the operational member is required, the assembly of the operational member is simplified, and the reduction of a manufacturing cost is attainable.
Moreover, making the setting and adjustment of the insensitive zone of the operational member performable by the electric processing eliminates the need for providing a conventional mechanical insensitive zone and enables the assembly of the operational member to be simplified and the reduction of a manufacturing cost to be achieved. The electric provision of the insensitive zone enables the size of the insensitive zone to be freely set and modified and further when portions of the insensitive zone are provided in both directions with respect to the standard position of the operational member, its portions can be easily allotted to both directions equally, thereby enabling the operability to be improved.